Reader and/or writer apparatus, power feeding system, and communication system

ABSTRACT

A reader and/or writer apparatus having an antenna lying substantially in a plane for generating an electromagnetic field to supply power to an IC card and a conductor member to be disposed in a plane substantially parallel to the plane of the antenna, wherein the distance between the antenna and the conductor member is no greater than 20 mm. A power supplying system supplies power using electromagnetic waves from the reader and/or writer apparatus to the IC card. The IC card includes a circuit for converting the supplied power to a D.C. voltage and for supplying the D.C. voltage to an internal circuit of the IC card.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a reader and/or writerapparatus, a power feeding system and a communication system forperforming power feeding for proximate wireless operation andcommunication between, for instance, a cash dispenser, electronic money,an automatic ticket checking system, a room entrance/exit managementsystem or a pay telephone and a proximate wireless card, such as a cashcard, a credit card, a passenger ticket, a commuting ticket, a couponticket, a control card, an IC card, a license or a telephone callingcard.

[0002] It is already known that, by using light or a magnetic field,electric power can be supplied in a non-contact manner from the powerfeeding side to a proximate wireless card (IC card).

[0003] For example, Japanese Patent No. 2626882 (JP-A-8-263609)discloses a technique related to disposing a metal plate on a back of acoil-shaped antenna to prevent wrong operation such as reading card datafrom a back of a non-contact card reader, especially a technique foradjusting a distance between the metal plate and the coil-shaped antennain consideration of the fact that the resonant frequency shifts when themetal plate is disposed.

[0004] In non-contact card systems (proximate wireless card systems),cash cards, credit cards, passenger tickets, commuting tickets and thelike for use at the gates of railway stations, on buses andexit/entrances are made as IC cards. When the user of such an IC cardcauses the IC card to pass in a non-contact manner through areader/writer provided at the gate of a railway station, on a bus or atan exit/entrance, a power feeding wave or a communication wave isradiated from a coil or an antenna of the reader and/or writer, thiselectromagnetic wave is received and induced by a coil or an antenna onthe card side to actuate a circuit on the card side and to detect asignal. In this case, an electric field radiated from the coil orantenna of the reader and/or writer should satisfy the requirement ofthe Wireless Telegraphy Act (500 μV/m at a distance of 3 m from thereader and/or writer).

[0005] However, there is involved the problem that, as theaforementioned requirement of the Wireless Telegraphy Act (500 μV/m at adistance of 3 m from the reader and/or writer) regarding the radiatedelectric field determines the upper limit of the amperage of the coil orantenna for the reader and/or writer and hence the upper limit of powerfeeding, it is difficult to feed sufficient power to the IC card. Thatis, there is involved the problem that sufficient power feeding from thereader and/or writer to the IC card at a desired distance from thereader and/or writer and suppression of a far field prescribed in theWireless Telegraphy Act is difficult.

SUMMARY OF THE INVENTION

[0006] In order to solve the aforementioned problems, a first object ofthe present invention is to provide a reader and/or writer apparatus, apower feeding system and a communication system in a proximate wirelesscard system arranged so that power which satisfies the requirement ofthe Wireless Telegraphy Act (500 μV/m at a distance of 3 m from thereader and/or writer apparatus) regarding the radiated electric fieldcan be supplied sufficiently from the reader and/or writer apparatus tothe proximate wireless card (IC card).

[0007] A second object of the invention is to provide a reader and/orwriter apparatus, a power feeding system and a communication system in aproximate wireless card system which performs high-efficiency powerfeeding by making acceptable an error in the positioning of the IC cardproximate to an antenna provided on the reader and/or writer apparatus.

[0008] In order to achieve the first object, according to one aspect ofthe present invention, a reader and/or writer apparatus has of aspirally shaped or coil-shaped antenna for generating an electromagneticfield to supply operational power to an IC card, and a conductor memberfor forming a mirror image of the antenna.

[0009] According to another aspect of the present invention, a readerand/or writer apparatus has a spirally shaped or coil-shaped antenna forgenerating electromagnetic fields both to supply operational power to anIC card and to transmit and/or receive signals for communication to/fromthe IC card, and a conductor member for forming a mirror image of theantenna.

[0010] The just-mentioned the reader and/or writer apparatus accordingto the present invention comprises a power supply for generating asignal for power feeding, an encoding circuit for encoding inputtedtransmit data, a modulator for amplitude-modulating the signal obtainedfrom the power supply with a signal obtained from the encoding circuitso that the signal obtained from encoding circuit is superimposed on thesignal obtained from the power supply, and a power feeding circuit forfeeding power to an antenna on the basis of a signal obtained from themodulator.

[0011] According to still another aspect of the present invention, areader and/or writer apparatus has a spirally shaped or coil-shapedantenna for generating an electromagnetic field to supply operationalpower to an IC card and a spirally shaped or coil-shaped image antennawhich constitutes a mirror image of the former antenna.

[0012] According to yet another aspect of the present invention, areader and/or writer apparatus has a spirally shaped or coil-shapedantenna for generating electromagnetic fields both to supply operationalpower to an IC card and to transmit and/or receive signals forcommunication to/from the IC card and a spirally shaped or coil-shapedimage antenna which constitutes a mirror image of the former antenna.

[0013] The just-mentioned reader and/or writer apparatus according tothe invention comprises a power supply for generating a signal for powerfeeding, an encoding circuit for encoding inputted transmit data, amodulator for amplitude-modulating the signal obtained from the powersupply with a signal obtained from the encoding circuit so that thesignal obtained from encoding circuit is superimposed on the signalobtained from the power supply, and a power feeding circuit for feedingpower to an antenna and an image antenna on the basis of a signalobtained from the modulator.

[0014] According to yet another aspect of the present invention, a powerfeeding system for feeding power, using electromagnetic waves, from areader and/or writer apparatus to an IC card, for converting, in the ICcard, the fed power to a D.C. voltage and for supplying this D.C.voltage to an internal circuit of the IC card, is provided wherein thereader and/or writer apparatus has a spirally shaped or coil-shapedantenna for generating an electromagnetic field to supply operationalpower to the IC card and a conductor member for forming a mirror imageof the antenna.

[0015] According to still another aspect of the present invention, acommunication system for feeding power, using electromagnetic waves,from a reader and/or writer apparatus to an IC card and for performingtransmission and/or reception of signals for communication to and/orfrom the IC card, is provided wherein the reader and/or writer apparatushas a spirally shaped or coil-shaped antenna for generating anelectromagnetic field both to supply operational power to the IC cardand to perform transmission and/or reception of signals forcommunication to and/or from the IC card and a conductor member forforming a mirror image of the antenna.

[0016] According to yet another aspect of the present invention, a powerfeeding system for feeding power, using electromagnetic waves, from areader and/or writer apparatus to an IC card, for converting, in the ICcard, the fed power to a D.C. voltage and for supplying this D.C.voltage to an internal circuit of the IC card, is provided wherein thereader and/or writer apparatus has a spirally shaped or coil-shapedantenna for generating an electromagnetic field to supply operationalpower to the IC card and a spirally shaped or coil-shaped image antennawhich constitutes a mirror image of the former antenna.

[0017] According to still another aspect of the present invention, acommunication system for feeding power, using electromagnetic waves,from a reader and/or writer apparatus to an IC card and for performingtransmission and/or reception of signals for communication to and/orfrom the IC card, is provided wherein the reader and/or writer apparatushas a spirally shaped or coil-shaped antenna for generating anelectromagnetic field both to supply operational power to the IC cardand to perform transmission and/or reception of signals forcommunication to and/or from the IC card and a spirally shaped orcoil-shaped image antenna which constitutes a mirror image of the formerantenna.

[0018] In the just-mentioned communication system, the reader and/orwriter comprises a power supply for generating a signal for powerfeeding, an encoding circuit for encoding inputted transmit data, amodulator for amplitude-modulating the signal obtained from the powersupply with a signal obtained from the encoding circuit so that thesignal obtained from encoding circuit is superimposed on the signalobtained from the power supply, and a power feeding circuit for feedingpower to an antenna and an image antenna on the basis of a signalobtained from the modulator.

[0019] According to still another aspect of the present invention, areader and/or writer apparatus has an antenna for generating anelectromagnetic wave to feed power to an IC card, and a conductor memberdisposed so that a·tan θ is 0.2 or less where a is a dimension of theantenna in a position where the distance between an outermost element ofthe antenna and an edge of the conductor member is minimum and θ is anangle formed between the conductor member and a line which connects theoutermost component of the antenna with the edge of the conductormember.

[0020] In the just-mentioned reader and/or writer apparatus, the antennaboth feeds power to the IC card and performs transmission and/orreception of a communication signal to and/from the IC card.

[0021] According to still another aspect of the present invention, apower feeding system for feeding power, using electromagnetic waves,from a reader and/or writer apparatus to an IC card, for converting, inthe IC card, the fed power to a D.C. voltage and for supplying this D.C.voltage to an internal circuit of the IC card, is provided wherein thereader and/or writer apparatus has an antenna for generating anelectromagnetic field to supply operational power to the IC card and aconductor member disposed so that a·tan θ is 0.2 or less where a is adimension of the antenna in a position where the distance between anoutermost component of the antenna and an edge of the conductor memberis minimum and θ is an angle formed between the conductor member and aline which connects the outermost component of the antenna with the edgeof the conductor member.

[0022] According to still another aspect of the present invention, acommunication system for feeding power, using electromagnetic waves,from a reader and/or writer apparatus to an IC card and for performingtransmission and/or reception of signals for communication to and/orfrom the IC card, is provided wherein the reader and/or writer apparatushas an antenna for generating an electromagnetic wave to feed power tothe IC card, and a conductor member disposed so that a·tan θ is 0.2 orless where a is a dimension of the antenna in a position where thedistance between an outermost element of the antenna and an edge of theconductor member is minimum and θ is an angle formed between theconductor member and a line which connects the outermost component ofthe antenna with the edge of the conductor member.

[0023] According to a feature of the present invention, a spirallyshaped or coil-shaped antenna for generating an electromagnetic wave tofeed power to an IC card and a conductor member for forming a mirrorimage of the antenna to suppress an electric field intensity at aposition at least 3 meters distant from the antenna, are provided.

[0024] According to another feature of present invention, a spirallyshaped or coil-shaped antenna for generating an electromagnetic waveboth to feed power to an IC card and to perform transmission and/orreception of a communication signal to and/or from the IC and aconductor member for forming a mirror image of the antenna to suppressan electric field intensity at a position at least 3 meters distant fromthe antenna.

[0025] According to still another aspect of the present invention, apower feeding system for feeding power, using electromagnetic waves,from a reader and/or writer apparatus to an IC card, for converting, inthe IC card, the fed power to a D.C. voltage and for supplying thisvoltage to an internal circuit of the IC card, is provided wherein thereader and/or writer apparatus has a spirally shaped or coil-shapedantenna for generating an electromagnetic wave to feed power to the ICcard and a conductor member for forming a mirror image of the antenna tosuppress an electric field intensity at a position at least 3 metersdistant from the antenna.

[0026] According to still another aspect of the present invention, acommunication system for feeding power, using electromagnetic waves,from a reader and/or writer apparatus to an IC card and for performingtransmission and/or reception of signals for communication to and/orfrom the IC card, is provided wherein the reader and/or writer apparatushas a spirally shaped or coil-shaped antenna for generating anelectromagnetic wave both to feed power to the IC card and to performtransmission and/or reception of a communication signal to and/or fromthe IC and a conductor member for forming a mirror image of the antennato suppress an electric field intensity at a position at least 3 metersdistant from the antenna.

[0027] In order to achieve the second object, according to an aspect ofthe present invention, a power feeding system for feeding power, usingelectromagnetic waves, from a reader and/or writer apparatus to an ICcard, for converting, in the IC card, the fed power to a D.C. voltageand for supplying this voltage to an internal circuit of the IC card, isprovided wherein the outermost dimensions of a spirally shaped orcoil-shaped antenna, provided in the reader and/or writer apparatus, forgenerating an electromagnetic field to supply operational power to theIC card is smaller than the outermost dimensions of a spirally shaped orcoil-shaped image antenna formed in the IC card.

[0028] According to another aspect of the present invention, acommunication system for feeding power, using electromagnetic waves,from a reader and/or writer apparatus to an IC card and for performingtransmission and/or reception of signals for communication to and/orfrom the IC card, is provided wherein outermost dimensions of a spirallyshaped or coil-shaped antenna, provided in the reader and/or writerapparatus, for generating electromagnetic waves both to supplyoperational power to the IC card and to perform transmission and/orreception of signals for communication to and/or from the IC card issmaller than outermost dimensions of a spirally shaped or coil-shapedimage antenna formed in the IC card.

[0029] As has been explained above, according to the above-describedconfiguration, in a reader and/or writer for feeding power to aproximate IC card, using electromagnetic waves (wireless), it ispossible to feed, from an antenna of the reader and/or writer to the ICcard, power which satisfies the requirements of the Radio Law in everydirection and moreover operates the proximate IC card stably.

[0030] Also, according to the above-described configuration, in a powerfeeding system for feeding power from a reader and/or writer to aproximate IC card, using electromagnetic waves (wireless), it ispossible to feed, from an antenna of the reader and/or writer to the ICcard, power which satisfies the requirements of the Radio Law in everydirection and moreover operates the proximate IC card stably.

[0031] Also, according to the above-described configuration, in a readerand/or writer for performing power feeding and communication to aproximate IC card, using electromagnetic waves (wirelessly) from asingle antenna, it is possible to feed, from an antenna to the IC card,power which satisfies the requirements of the Radio Law in everydirection and moreover operates the proximate IC card stably to therebyperform stable communication.

[0032] Also, as in the above-described configuration, by providing aconductor plate under the antenna, a shielding effect is achieved, whichensures stable operation free from the effect of the electromagneticwaves (noise) even if a high-frequency electronic circuit is providedfurther under the conductor plate.

[0033] As in the above arrangement, by making smaller the outermost sizeof the spirally shaped or coil-shaped antenna for generating anelectromagnetic field to feed power to the IC card provided in thereader and/or writer apparatus than the outermost size of the spirallyor coil-shaped antenna formed in the IC card, an error in thepositioning of the IC card provided close to the antenna provided in thereader and/or writer apparatus is acceptable. It is preferable from astandpoint of the number of magnetic fluxes which are interlinked withthe antenna of the IC card that the outermost periphery of the antennaof the IC card is h or more larger than the outermost periphery of theantenna of the reader and/or writer apparatus where h is acommnunication distance between the reader and/or writer apparatus andthe IC card in a state where the center of the antenna of the readerand/or writer apparatus and the center of the antenna of the IC cardconincide substantially.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034]FIG. 1 is a perspective view of a schematic configuration of apower feeding and communication system for feeding power wirelessly andalso for performing communication wirelessly from a reader and/or writerunit (apparatus) according to the present invention to a proximatewireless card (IC card).

[0035]FIG. 2 is a schematic of one embodiment of an apparatus (system)for feeding electric power wirelessly and for performing communicationwirelessly between the reader and/or writer apparatus and the proximatewireless card (IC card) according to the invention.

[0036]FIG. 3 illustrates the relationship between a power feeding waveand a modulated wave for data communication according to the invention.

[0037]FIG. 4 illustrates the relationship between a reader and/or writerantenna provided in the reader and/or writer apparatus and the IC cardaccording to the invention.

[0038]FIG. 5 is a perspective view of a first embodiment of the readerand/or writer antenna provided on the reader and/or writer according tothe invention.

[0039]FIG. 6 is a diagram for explaining the principle of synthesizingmagnetic fields in each of vertical direction and a side direction inthe first embodiment of the reader and/or writer antenna.

[0040]FIG. 7 is a diagram of a simulated field strength with a verticaldistance from a reader and/or writer antenna of the first embodiment.

[0041]FIG. 8 is a diagram of a simulated field intensity in a position 3[m] spaced sideways from the reader and/or writer antenna of the firstembodiment.

[0042]FIG. 9 is a perspective view of a second embodiment of the readerand/or writer antenna provided on the reader and/or writer apparatusaccording to the invention.

[0043]FIG. 10 is a perspective view of a modification of the secondembodiment of the reader and/or writer antenna provided on the readerand/or writer apparatus according to the invention.

[0044]FIG. 11 is a diagram of a simulated electric field intensity 3meters spaced from a reader and/or writer circular-loop antenna with aconductor plate disposed.

[0045]FIG. 12 is a diagram of a simulated electric field intensity 3meters spaced from a reader and/or writer rectangular-loop antenna witha conductor plate disposed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] Embodiments of the present invention will be described next,using the accompanying drawings.

[0047] Described first will be a power feeding system for non-contactcard operation and an antenna used therefor in a reader and/or writer ofone of cash dispensers, electronic money, automatic ticket checkingsystems, and room entrance/exit control systems, etc., and anappropriate one of non-contact cards including cash cards, credit cards,passenger tickets, commuting tickets, coupon tickets, control cards, ICcards, licenses, telephone cards, highway toll cards and the like foruse in the cash dispensers, electronic money, automatic ticket checkingsystems, and room entrance/exit control systems, etc.

[0048]FIG. 1 is a diagram illustrating a schematic configuration of apower feeding and communication system for feeding power and alsoperforming communication from a reader and/or writer unit (apparatus) 1according to the invention, for example, provided at a ticket checkinggate, on a bus, at an entrance/exit or in a prescribed place, to anon-contact card 2 (proximate wireless card: IC card) which is caused topass through the reader and/or writer in a non-contacting manner or bebrought close to the reader and/or writer. The non-contact card(proximate wireless card: IC card) 2 serves as a cash card, credit card,passenger ticket, commuting ticket or the like as it is caused to passby the reader and/or writer provided at a ticket checking gate, on abus, or at an entrance/exit with the IC card being held by its user in anon-contacting manner, for example, at a distance of up to about 20 cmfrom the reader and/or writer unit 1 by transmitting and/or receivingwirelessly information on the cash card, credit card, passenger ticket,commuting ticket or the like to/from the reader and/or writer. Thenon-contact card (proximate wireless card: IC card) 2 may also be usedwithout contacting with the reader and/or writer 1 in a roughly fixedposition at a comparatively constant distance h of about a few cm orless from the reader and/or writer. In this case, by making thedimensions of a card antenna 201 formed on the proximate wireless card 2greater than the dimensions of an R/W antenna 101 provided on the readerand/or writer unit 1, both power feeding and transmission and/orreception of communication are accomplished stably by usingelectromagnetic waves (wireless) consisting of a power feeding wave anda modulated wave for data communication between the reader and/or writerantenna 101 and the card antenna 201 even if the card antenna 201deviates somewhat from the reader and/or writer antenna 101.

[0049]FIG. 2 is schematic of one embodiment of an apparatus (system) forfeeding electric power wirelessly and for performing transmission and/orreception (communication) of information wirelessly between the readerand/or writer unit (apparatus) 1 and the non-contact card 2 (proximatewireless card: IC card) according to the invention. The embodiment ofFIG. 2 illustrates performing both the feeding of power and thetransmission and/or reception of communication using electromagneticwaves (wirelessly) consisting of a power feeding wave and a modulatedwave for data communication illustrated in FIG. 3 between the readerand/or writer antenna provided in the reader and/or writer unit 1 andthe card antenna 201 formed on the proximate wireless card 2. Although apower feeding wave and a signal wave in such ASK modulation system aredifferent in frequency component in terms of frequency region, only theamplitude of the power feeding wave varies with the signal velocity interms of time region. In other words, a modulated wave resulting frommultiplying the signal wave by the power feeding wave only looks likethe up and down fluctuations of the amplitude of the power feeding wavein terms of time region. Though it is conceivable to transmit the powerfeeding wave and the signal wave over separate antennas where themodulated wave is to be transmitted wirelessly, the inventiveconfiguration is such that the field intensity is limited within therequirement of the Radio Law (500 μV/m at a distance of 3 m) and thismodulated wave is transmitted over a single antenna (reader and/orwriter antenna) 1 with a view to simplifying the non-contact card(proximate wireless card: IC card) 2.

[0050] Thus the reader and/or writer unit 1 is provided with a powersupply source 105 for generating a voltage at a high frequency of 13.56MHz; an encoding circuit 107 for encoding transmit data 106 inputted fortransmission to the proximate wireless card 2; a modulator 108 forsuperposing (multiplying) amplitude modulation (Amplitude Shift Keyingmodulation) on (by) the high-frequency voltage of 13.56 MHz generated bythe power supply source 105, using the signal encoded by the encodingcircuit 107; a transmission amplifier 109 for amplifying the signalASK-modulated on the high-frequency voltage of 13.56 MHz by themodulator 108; a matching circuit (power feeding circuit) 102 includinga capacitor 104 for coupling by inductance coupling 103 the signalamplified via the transmission amplifier 109 thereto, to performimpedance matching to prevent reflection; the reader and/or writerantenna 101 for generating electromagnetic waves to feed power andtransmit data to the card 2 depending on the output of the matchingcircuit 102 and for receiving data transmitted by an electromagneticwave from the card antenna 201 of the proximate wireless card 2; afilter circuit 110 for having the signals received by the R/W antenna101 matched in the matching circuit 102 and for removing noisecomponents from the signal generated by the inductance coupling 103; areception amplifier 111 for amplifying a signal obtained through thefilter circuit 110; a demodulator 112 for demodulating the signalamplified by the reception amplifier 111, using the high-frequencyvoltage signal of 13.56 MHz obtained from the power supply circuit 105;and a decoding circuit 113 for decoding the signal demodulated by thedemodulator 112 and for outputting them as receive data 114. Thetransmit data 106 and the receive data 114 are coupled to a hostcomputer 115 via a network.

[0051] The non-contact card (proximate wireless card: IC card) 2 isprovided with the card antenna 201 for receiving the electromagneticwaves generated from the reader and/or writer antenna 101 of the Readerand/or writer unit 1 to perform power feeding and data transmission, andfor generating an electromagnetic wave corresponding to loadswitching-modulated transmit data; a wireless chip 202 having a matchingand rectifying circuit 203 for rectifying the power of 13.56 MHzreceived by the card antenna 201 and for impedance-matching the transmitand/or receive signals, a power supply circuit 204 for supplying aconstant D.C. voltage power supply 205 of about 2 to 5 V in about 5 mWfrom the rectified induced voltage from the matching and rectifyingcircuit 203, a clock extracting circuit 206 for extracting a clocksignal from the receive signal obtained from the matching and rectifyingcircuit 203, an LPF circuit 207 for removing noise components from thereceive signal obtained from the matching and rectifying circuit 203, awaveform shaping circuit 208 for waveform-shaping the receive signalobtained from the LPF circuit 207, and a load switching-modulatingcircuit 209 for load switching-modulating a transmit signal, for givingthe modulated signal to the matching and rectifying circuit 203 formatching purposes and for supplying the matched signal to the card coil201; and a chip 210 including a CPU (CPU+interface) having a frequencydividing circuit 211 for generating a signal which is frequency-dividedon the basis of the clock signal extracted by the clock extractingcircuit 206 of the wireless chip 202 and for operating a microcomputer214, a decoding circuit 212 for decoding the signal obtained from thewaveform shaping circuit 208 of the wireless chip 202 and for inputtingthis signal to the microcomputer (CPU) 214 as decoded data (receivedata), an encoding circuit 216 for encoding transmit data obtained fromthe microcomputer 214 and for inputting the encoded data to the loadswitching-modulating circuit 209 of the wireless chip 202, and themicrocomputer (CPU) 214 of H8 or the like, with a built-in memory forstoring information as a card, for processing transmit and/or receivedata and for transferring data to and from the memory, and for receivingthe stable power supply 205 from the power supply circuit 204 of thewireless chip 202.

[0052] The use of the reader and/or writer antenna 101 and the cardantenna 201 for feeding power on an electromagnetic wave (wirelessly) isintended to improve the efficiency of power feeding by electromagneticinduction utilizing magnetic coupling. Where a spirally shaped antenna201 is formed on the proximate wireless card 2, there is an advantage ofresisting deformation of the proximate wireless card 2. Both the readerand/or writer antenna 101 and the card antenna 201 may take the form ofa coil.

[0053] As has been described above, in the proximate wireless cardsystem, by bringing the non-contact card (proximate wireless card: ICcard) 2 close to the reader and/or writer 1, for example, at acomparatively constant distance h of about a few cm or less, power isfed wirelessly and also transmission/reception of information(communication) is also accomplished wirelessly between the readerand/or writer unit 1 and the non-contact card 2. Thus, in the proximatewireless card system, a power feeding wave or a communication wave isradiated from the reader and/or writer antenna 101, and thiselectromagnetic wave is received and induced by the spirally shaped orcoil-shaped antenna 201 on the card side to operate the card sidecircuit to detect a signal.

[0054] Now, in the proximate wireless card system, when the non-contactcard (proximate wireless card: IC card) 2 is brought close to the readerand/or writer 1 at a comparatively constant distance h of about a few cmor less and used, as illustrated in FIG. 4, the spirally shaped antenna101 to be used in the reader and/or writer 1 is configured by forming,over an insulating substrate 101 a, a spirally shaped or coil-shapedantenna 101 b of a filmy conductor having an outer rectangular shapewhose outermost contour measures 25 mm to 75 mm. In this case, it issufficiently small relative to a wavelength of 22 m determined by aservice frequency of 13.56 MHz, and the current distribution on theantenna is considered to be substantially uniform. As a result, a highelectric field and a high magnetic field are generated in the side andvertical directions, respectively, of the antenna.

[0055] In this case, if the non-contact card 2 with a spirally shaped orcoil-shaped antenna 201 mounted in the vertical direction is brought ata distance h of about a few cm or less from the reader and/or writer,the power feeding wave or the signal wave can be transmitted/received.This communication distance can increase up to about 20 cm depending onthe ability of the system. However, if the radiated electric field islimited to within the requirement of the Radio Law (500 μV/m at adistance of 3 m), the upper limit of the amperage to be fed to thespirally shaped antenna or coil 101 b for the reader and/or writer isdetermined, the upper limit of the intensity of the magnetic fieldnecessary for power feeding is determined, and hence the upper limit ofpower feeding is limited.

[0056] Therefore, it is desired that the antenna 101 to be used in thereader and/or writer 1 satisfy the requirement of the Radio Law (500μV/m at a distance of 3 m) regarding the radiated electric field andmoreover make possible sufficient power feeding to the non-contact card(proximate wireless card: IC card) 2.

[0057] Described next will be embodiments of the antenna 101 provided onthe reader and/or writer 1 according to the present invention, whichsatisfies the requirement of the Radio Law (500 μV/m at a distance of 3m) regarding the radiated electric field and moreover makes possiblesufficient power feeding to IC card 2.

[0058] First will be described a first embodiment of the antenna 101provided on the reader and/or writer 1 according to the invention. FIG.5 illustrates the first embodiment of the antenna 101 provided on thereader and/or writer 1 according to the invention. As the firstembodiment of the antenna 101 to be used on the reader and/or writer 1,it is configured by forming, on an insulating substrate 101 a, thespirally shaped or coil-shaped antenna 101 b of a filmy conductor havingan outer rectangular shape whose outermost contour measures 25 mm to 75mm, and providing, on the back side of this substrate 101 a, a conductorplate (metal plate) 101 c of Cu or the like, which forms a mirror image91 of the antenna 101 b at a close distance of d=about 20 mm or less tothe antenna 101 b. The conductor plate (metal plate) 101 c is groundedto stabilize the electric potential. The conductor plate 101 c ispreferably made of a metal easy to form the mirror image 91 and havinglow resistance such as Cu or Al.

[0059] As a result of the provision of this conductor plate (metalplate) 101 c to form the mirror image 91 of the antenna 101 b at theclose distance of d=about 20 mm or less to the spirally shaped orcoil-shaped antenna 101 b, magnetic fields at points at distances of r1and r3 from the sides of the antenna (loop antenna) 101 b excited at13.56 MHz in a vertical direction to cause a current I to flow throughthe antenna and magnetic fields at points at distances of r1′ and r3′from the sides of the mirror image 91 formed at a distance of 2 d fromthe antenna (loop antenna) 101 b are synthesized as shown in FIG. 6.

[0060] The magnetic field at a distance of D[m] upward from the readerand/or writer is measured with a measuring loop antenna (a square loopantenna of which each side is 61.6 cm long), and its field intensityequivalent (ωμSHz×AF)[dBuV/m] is obtained, as illustrated in FIG. 7.FIG. 7 shows, with the spirally shaped or coil-shaped antenna (loopantenna) 101 b, of which the maximum external dimensions are 30 mm×30mm, the number of turns [T] is 5 and the current Is=1.0 [Arms], theresult of simulation of the relationship between the distance D[m]upward from the reader and/or writer and the field intensity [dBuV/m] atthat distance with respect to a case in which the conductor plate (metalplate) 101 c is absent and to cases in which the conductor plate (metalplate) 101 c is present and d=5 [mm], d=20 [mm], and d=50 [mm]. FIG. 7shows that where the conductor plate (metal plate) 101 c is present, thefield intensity is reduced more conspicuously, as the upward distance Dincreases, than where the conductor plate (metal plate) 101 c is absent.As the distance d between the loop antenna 101 b and the metal plate 101c decreases from 50 [mm] through 20 [mm] to 5 [mm], the field intensityis reduced when the upward distance D is large.

[0061] The Radio Law requires that the field intensity at D=3 [m] be 54[dBuV/m].

[0062] Therefore, if, at D=3 [m], the distance d between the loopantenna 10 b and the metal plate 101 c is set at 5 [mm] or less, thefield intensity is reduced by at least 41 [dBuV/m] compared to the casewhere the metal plate is absent.

[0063] Then, if, for instance, the distance d between the loop antenna101 b and the metal plate 101 c is set at 5 [mm] or less, and when thedistance between the loop antenna 101 b and the IC card 2 is set at afew cm or less, it is possible to feed power from the loop antenna 101 bto the card antenna 201 until the electric field intensity is up toabout 190 [dBuV/m] or more. If, for example, the distance d between theloop antenna 101 b and the metal plate 101 c is set at 20 [mm], and whenthe distance between the loop antenna 101 b and the IC card 2 is set ata few cm or less, it is possible to feed power from the loop antenna 101b to the card antenna 201 until the field intensity is up to about 180[dBuV/m] or more.

[0064] In order to satisfy the requirement of the Wireless TelegraphyAct (54 [dBuV/m] at D=3 [m])in the absence of the metal plate, it willbe necessary to bring down the field intensity based on the power fedfrom the loop antenna 101 b to the card antenna 201 to about 120[dBuV/m] or less. However, by installing the metal plate 101 c on theback side of the loop antenna 101 b as stated above, the requirement ofthe Wireless Telegraphy Act regarding the radiated field intensity (500μ/Vm at a distance of 3 m) is satisfied and sufficient power is fed tothe IC card 2.

[0065] Also, as illustrated in FIG. 6, by the provision of the conductorplate (metal plate) 101 c to form the mirror image 91 of the antenna 101b at a close distance of d=about 20 mm or less to the spirally shaped orcoil-shaped antenna 101 b, electromagnetic fields (mainly electricfields) at points at distances of r1 and r3 from the sides of theantenna (loop antenna) 101 b excited at 13.56 MHz in a side direction tocause a current I to flow through the antenna, and electromagneticfields (mainly electric fields) at points at distances of r1′ and r3′from the sides of the mirror image 91 formed at a distance of 2 d fromthe spirally shaped or coil-shaped antenna (loop antenna) 101 b aresynthesized. Thus, a field intensity of [dBuV/m] in a position 3[m]sideways from the loop antenna 101 b is as shown in FIG. 8. FIG. 8 alsoshows, with the spirally shaped or coil-shaped antenna (loop antenna)101 b, of which the maximum external dimensions are 30 mm×30 mm, thenumber of turns [T] is 5, and the current Is=1.0 [Arms], the result ofsimulation of the relationship of the field intensity [dBuV/m] in aposition 3 [m] sideways from the loop antenna 101 b to an angle φ aroundthe loop antenna 101 b with respect to a case in which the conductorplate (metal plate) 101 c is absent and cases in which the conductorplate (metal plate) 101 c is present and d=5 [mm], d=10 [mm], d=20 [mm],d=30 [mm], d=40 [mm], and d=50 [mm]. As shown in FIG. 8, where theconductor plate (metal plate) 101 c is present, the field intensity isreduced by a minimum of 45 [dBuV/m] even when d=50 [mm] compared to thecase where the conductor plate (metal plate) 101 c is absent. Thus, byproviding the metal plate 101 c on the back side of the loop antenna 101b, the requirement of the Radio Law (54 [dBuV/m] of field intensity atD=3 [m]) is readily satisfied in the side direction rather than in thevertical direction from the loop antenna 101 b.

[0066] Similar values to the results of simulation regarding the fieldintensity in the presence and absence of the metal plate in FIGS. 7 and8 were confirmed in experiments.

[0067] As has been described above, by providing the metal plate 101 con the back side of the loop antenna 101 b, it is ensured that theradiated electric field satisfies the requirement of the WirelessTelegraphy Act (500 dBuV/m at D=3 m) in every direction of the loopantenna 101 b and, moreover, that sufficient power is fed to the cardantenna 201 of the IC card 2.

[0068] Obviously, a field intensity for the modulated wave for datacommunication radiated from the loop antenna 101 b readily satisfies therequirement of the Radio Law (500 dBuV/m at D=3 m) because it is lowerthan the power feeding wave.

[0069] Described next will be a second embodiment of the antenna 101provided on the reader and/or writer 1 according to the presentinvention. FIG. 9 illustrates the basic concept of the second embodimentof the antenna 101, which is configured by connecting a spirally shapedor coil-shaped image antenna (image loop antenna) 101 d to a spirallyshaped or coil-shaped antenna 101 b in its mirror image position. Asshown in FIG. 9, the current to flow through the antenna 101 b and thecurrent to flow through the image antenna 101 d are made inverse indirection to each other. By using such configuration, it is ensured thatthe image antenna 101 d performs the same function as the mirror image91, which is formed by the metal plate 101 c in the first embodiment,that the radiated electric field satisfies the requirement of theWireless Telegraphy Act (500 dBuV/m at D=3 m) in every direction of theloop antenna 101 b and, moreover, that sufficient power is fed to thecard antenna 201 of the IC card 2. In this case, it is necessary tocoordinate the high-frequency current of 13.56 MHz to flow through theantenna 101 b and the high-frequency current of 13.56 MHz to flowthrough the image antenna 101 d to be either the same in direction andreverse in phase, or reverse in direction and the same in phase.Therefore, it is necessary to determine the coil lengths so that thehigh-frequency current of 13.56 MHz to flow through the antenna 101 bcoincides in phase with the high-frequency current of 13.56 MHz to flowthrough the image antenna 101 d.

[0070]FIG. 10 is a perspective view of an example in which the antenna101 b and the image antenna 101 d are driven by separate amplifiers 109a and 109 b, respectively. By using such configuration and inputtinghigh-frequency signals of the same 13.56 MHz to the drive amplifiers 109a and 109 b, the currents to flow through the antennas 101 b and 101 deasily coincide in phase.

[0071] As has been described above, while the first embodiment preventsgeneration of a magnetic field on the back side of the metal plate 101c, the second embodiment allows generation of a similar magnetic fieldto that on the front side on the back side of the image antenna 101 d.If this magnetic field causes trouble, it will be necessary to provide aconductor plate such as a metal plate on the back side of the imageantenna 101 d to thereby prevent a generated magnetic field fromreaching an area remote from the back side of the image antenna 101 d.

[0072] Further, while both the feeding of power and thetransmission/reception of communications using electromagnetic waves(wireless) shown in FIG. 3 consisting of a power feeding wave and amodulated wave for data communication, between the reader and/or writerantenna 101 provided on the Reader and/or writer unit 1 and the cardantenna 201 formed on the IC card 2 have been described in the firstsecond embodiments mentioned above, the present invention is alsoeffective in the feeding of power using an electromagnetic waveconsisting only of a power feeding wave. For communication in this case,transmission/reception is performed using antennas provided separatelyfor the reader and/or writer unit 1 and the IC card 2.

[0073] Next, the relationship between the sizes of the antenna 101 b andmetal plate 101 c which satisfies the requirement of the Radio Law at adistance of 3 m and the distance between the antenna 101 b and metalplate 101 c will be described.

[0074]FIG. 11 shows a result of an experiment on an electric fieldintensity E generated at a distance of 3 m from a reader and/or writerwhich is provided with a circular antenna 101 b having a radius of a[m]and a conductor plate 110 c provided on the back of the antenna 101 bwhen a·tan θ which prescribes the relationship between the sizes of theantenna 101 b and metal plate 101 c and the distance between the antenna101 b and metal plate 101 c was changed. Note that the relationshipa·tan θ represents a ratio of the distance between the antenna 101 b andthe metal plate 101 c to a dimension of that portion of the metal plate101 c which extends further from the footprint of the antenna 101 b.FIG. 11 also shows a result of an experiment on each of products of acurrent which flows through the antenna and its number of turns.

[0075] As will be seen in FIG. 11, as a·tan θ increases, or the productof the antenna current and its number of turns increases, the electricfield intensity E increases. Thus, a·tan θ is required to be 0.2 or lessin order to maintain an electric field intensity E at a distance of 3 mfrom a reader and/or writer of 50 [ma·T] or more lower than 54 dBuV/m orless which is prescribed by the Radio Law.

[0076] While in FIG. 11 the experiment (simulation) was performed, usingantennas of sizes a=0.03, 0.05, 0.07, 0.10, 0.15 and 0.20 [m], even useof antennas of other sizes indicate substantially the samecharacteristics as those of FIG. 11 if the length of the antenna line is3 cm-3 m because the length of the antenna line is negligible comparedto the wavelength (22 m) (13.56 MHz) of the power feeding wave appliedto the reader and/or writer. This applies likewise to results of thefollowing experiments.

[0077]FIG. 12 shows a result of an experiment on an electric fieldintensity E generated at a distance of 3 m from a reader and/or writerwhich is provided with a rectangular antenna 101 b having a side of a[m] and a conductor plate 101 c provided on the back of the antenna 101b when a·tan θ which prescribes the relationship between the sizes ofthe antenna 101 b and metal plate 101 c and the distance between theantenna 101 b and metal plate 101 c was changed. FIG. 12 also shows aresult of an experiment on each of products of a current which flowsthrough the antenna and its number of turns.

[0078] As will be seen in FIG. 12, as a·tanθ increases, or the productof the antenna current and its number of turns increases, the electricfield intensity E increases. Thus, a·tan θ is required to be 0.2 or lessin order to maintain an electric field intensity E at a distance of 3 mfrom a reader and/or writer of 50 [ma·T] or more lower than 54 dBuV/m orless which is prescribed by the Radio Law.

[0079] As will be seen from the comparison of FIGS. 11 and 12, theelectric field intensity E does not extremely change depending on theshape of the antenna used, but relates to an area (through which themagnetic flux passes) formed by the outermost component of the antenna.Thus, in the case of other antenna shapes, the a·tan θ is required to be0.2 or less in a cross section of a place where the distance between theconductor plate edge 101 c and the outermost component of the antenna101 b is minimum.

[0080] With the antenna like those of FIGS. 11 and 12, it has beenconfirmed that a satisfactory magnetic field intensity is obtained at adistance of about 20 cm or less from the reader and/or writer on thebasis of its antenna current and its number of turns.

[0081] According to the present invention, in a reader and/or writerwhich feeds power to a proximate IC card, using an electromagnetic wave(wirelessly), it is possible to feed power which satisfies therequirement of the Radio Law in every direction of the antenna andmoreover operates the proximate IC card stably.

[0082] Also, according to the invention, in a power feeding system whichfeeds power from a reader and/or writer to a proximate IC card, using anelectromagnetic wave (wireless), it is possible to feed to the IC powerwhich satisfies the requirement of the Radio Law in every direction ofthe antenna and moreover operates the proximate IC card stably.

[0083] Also, according to the invention, in a reader and/or writer whichfeeds power to and communicates with a proximate IC card, using anelectromagnetic wave (wirelessly) radiated by a single antenna, it ispossible to feed to the IC card power which satisfies the requirement ofthe Radio Law in every direction of the antenna and operates theproximate IC card stably to thereby perform stable communication withthe IC card.

[0084] Also according to the invention, there is achieved, by providinga conductor plate under the antenna, a shielding effect which ensures,even if a high-frequency electronic circuit is configured further underthe high-frequency electronic circuit, stable operation of theelectronic circuit not subject to the effect of electromagnetic waves(noise).

1. A reader and/or writer apparatus comprising an antenna lyingsubstantially in a plane for generating an electromagnetic field tosupply power to an IC card and a conductor member to be disposed in aplane substantially parallel to the plane of the antenna, a distancebetween the antenna and the conductor member being no greater than 20mm.
 2. The reader and/or writer apparatus according to claim 1 ,comprising a power supply for generating a signal for supplying power,an encoding circuit for encoding inputted transmit data, a modulator foramplitude-modulating the signal obtained from the power supply with asignal obtained from the encoding circuit so that the signal obtainedfrom encoding circuit is superimposed on the signal obtained from thepower supply, and a power supplying circuit for supplying power to theantenna on the basis of a signal obtained from the modulator.
 3. Thereader and/or writer apparatus according to claim 1 , wherein the ICcard is a non-contact proximate wireless IC card.
 4. The reader and/orwriter apparatus according to claim 1 , wherein the antenna is aspirally shaped or coil-shaped antenna.
 5. The reader and/or writerapparatus according to claim 1 , wherein the conductor member is made ofCu or Al.
 6. A power supplying system for supplying power, usingelectromagnetic waves, from a reader and/or writer apparatus to an ICcard, the IC card having a circuit for converting the supplied power toa D.C. voltage and for supplying the D.C. voltage to an internal circuitof the IC card, the reader and/or writer apparatus having an antennalying substantially in a plane for generating an electromagnetic fieldto supply power to the IC card and a conductor member to be disposed ina plane substantially parallel to the antenna, the distance between theantenna and the conductor member being no greater than 20 mm.
 7. Thepower supplying system according to claim 6 , wherein said reader and/orwriter apparatus includes a power supply for generating a signal forsupplying power, an encoding circuit for encoding inputted transmitdata, a modulator for amplitude-modulating the signal obtained from thepower supply with a signal obtained from the encoding circuit so thatthe signal obtained from encoding circuit is superimposed on the signalobtained from the power supply, and a power supplying circuit forsupplying power to the antenna on the basis of a signal obtained fromthe modulator.
 8. The power supplying system according to claim 6 ,wherein said IC card is a non-contact proximate wireless IC card.
 9. Thepower supplying system according to claim 6 , wherein the antenna is aspirally shaped or coil-shaped antenna.
 10. The power supplying systemaccording to claim 6 , wherein the conductor member is made of Cu or Al.